Beside polyols, polyamines are the most important reactants for the isocyanate polyaddition process. The urea linkages formed when amino groups are added to isocyanates result in high molecular weight compounds which have interesting commercial properties. Polyfunctional amines may also be used as mixtures with other reactants for isocyanates, for example, polyols. The course of the reaction and the properties of the end product can be determined within wide limits by adjusting the proportions of the components in the mixture.
Whereas low molecular weight polyamines are easily prepared on an industrial scale and a wide choice is therefore available, the problem of preparing higher molecular weight diamines and polyamines has not hitherto been solved satisfactorily. This is partly because the processes employed in low molecular weight chemistry for synthesizing amines cannot easily be applied to higher molecular weight compounds and partly because the preparation of suitable high molecular weight starting compounds also often leads to difficulties.
It is therefore an object of the present invention to provide a simple and reproducible process for the preparation of higher molecular weight diamines and polyamines using steps of chemical synthesis which are easily carried out in practice.